The present invention relates generally to bicycle pedal systems. More specifically, the present invention is a simplified clipless pedal system including a pedal assembly and a cleat for attaching the sole of a cycling shoe to a bicycle.
Traditionally, more serious cyclists have used a system where a specialized, cleated cycling shoe is secured to a complementary pedal using a strap, or toe-clip. Using this system, the cyclist starts riding and then tightens the strap, or toe-clip. Stopping required that the rider first loosen the strap, allowing the shoe, and the cyclist""s feet, to be disengaged from the pedal. This system had the advantages of being simple, light and effective when used by experienced cyclists in appropriate conditions.
Unfortunately, the use of toe-clips also had a number of serious disadvantages. Most serious of these was the inability of the rider to disengage his feet from the pedals in case of an unexpected or emergency stop. This became especially serious with the increase in popularity of mountain bikes. Mountain bikes are most often used in off-road conditions. This type of riding is often far less predictable than more traditional cycling. As a result, unexpected or emergency stops are far more common and the riders of mountain bikes have a much greater need to be able to rapidly separate themselves from their bicycles.
The need for better bicycle pedal systems lead to the development of a number of different clipless pedal systems. These pedal systems include cleats which are affixed to the bottom of cycling shoes. The pedal includes a binding system which locks to the cleat to hold the shoe and the pedal together. The rider releases the cleat from the binding system by twisting the cleat in the pedal. Thus, the clipless pedal provides the rider with a secure connection to the pedal, and still allows the rider to rapidly disengage in the event of an unexpected stop.
Not surprisingly, clipless pedals have become increasing popular and, to a large extent, have actually replaced other pedal types. However, there are a few disadvantages associated with current clipless pedal designs. One disadvantage is complexity. Generally, the binding systems included in most clipless pedal designs include a number of moving parts. The bearings which support the pedal on the axle, or spindle, include still more moving parts. Many clipless pedals also include a number of different non-moving parts. These include, for example guides which help establish the position of the cleat within the binding system. The overall result is that a single pedal may include a large number of parts, increasing the manufacturing cost of each pedal. Worse, for many current clipless designs, the number of different parts is increased further by the requirement that the same part be provided in two mirrored versions, one for the right pedal and one for the left pedal, once again increasing manufacturing costs. The complexity of many clipless designs may also lead to a decrease in pedal durability. This is particularly true for mountain bike pedals whose components are required to function in dirt filled and otherwise hostile environments.
A second disadvantage of current clipless designs is weight. Generally, the binding system of most clipless pedals functions as a type of clamp. To be effective, the clamp must be supported by a rigid pedal platform. At the same time, the entire pedal assembly must be relatively small. The result has been that most clipless pedals have been constructed primarily from metals of various types making clipless pedal designs somewhat heavier than comparable toe-clip designs. In the weight conscious world of cycling, however, it is always desirable to find methods for making each component as light as possible.
A third disadvantage concerns rotation of the rider""s shoe relative to the pedal. Traditionally, in toe-clip pedal systems, the rider""s shoe is allowed a certain degree of unrestrained rotation with respect to the pedal. This unrestrained rotation is commonly known as xe2x80x9cfloatxe2x80x9d and generally results from the rather imprecise connection between the rider""s shoe and the pedal provided by most toe-clip designs. The more precise connection provided by early clipless designs largely eliminated float, resulting in a number of complaints from riders who found that they preferred pedal systems which provide at least some degree of float.
The response has been to add some degree of float to clipless pedal designs. This has been accomplished by providing specialized cleats or by changing the basic cleat design to allow for rotation of the cleat within the binding system. Generally, however, it has been found that different riders prefer differing degrees of float. To accommodate these differences in preference, manufactures have offered a selection of different cleats. Unfortunately, the cleat is an expensive part of the pedal system and this cost tends to prevent many cyclists from purchasing the range of cleats offered by manufactures. As a result, cyclists are discouraged from experimenting with a range of cleats to find the degree of float that best suits their particular style of riding.
The present invention is a simplified, highly-integrated and lightweight clipless pedal system for bicycles. Structurally, the pedal assembly of the present invention includes a unitary structure formed as a pedal platform shaped as a substantially rectangular solid and band which surrounds the pedal platform. Preferably, the pedal platform and band are formed from a plastic material and have an upper surface and a lower surface. Between the upper and lower surfaces, the rectangular shape of the pedal platform has four sides, with two sides being major sides and two sides being minor sides.
The band of the pedal structure has a substantially rectangular solid shape and encircles a similarly shaped inner opening. Between the upper and lower surfaces, the band has four outer sides with two sides being major sides and two sides being minor sides. The band also has four inner sides with two sides being major sides and two sides being minor sides.
The pedal platform and band are disposed in a concentric arrangement with the platform positioned inside of the inner opening of the band. The band is dimensioned so that the size of the inner opening exceeds the size of pedal platform, leaving a gap between each side of the pedal platform and each inner side of the band. This gap is spanned, or siameased, by two webbings which connect each major side of the pedal platform with an inner major side of the band.
The pedal assembly also includes a first cleat retainer and a second cleat retainer. Each cleat retainer is formed to have an elongated U-shape with a flat central portion and two bent, or hooked, ends. Each flat portion is formed with a pivot hole. Each cleat retainer is positioned with its flat portion against one of the minor sides of the pedal platform and with its two hooked ends projecting above opposite surfaces of the pedal platform. Additionally, the cleat retainers are oriented so that the hooked ends of the cleat retainers face each other. Thus, two facing hooked cleat retainer ends project from each surface of the pedal platform.
Two set screws are included in the pedal assembly. Each set screw is formed to have a proximal threaded portion that abruptly narrows to a distal projection. A shoulder is formed at the transition between the proximal threaded portion and the distal projection of each set screw.
Each minor side of the band is formed with a threaded hole. One set screw is threadably inserted through each of these holes. The set screws are adjusted so that the distal projections pass through the pivot holes in the cleat retainers. When correctly adjusted, the shoulder of each set screw urges against the central portion of one of the cleat retainers, each set screw thereby serving as a stop. The cooperation between the pedal platform, cleat retainers, band and set screws allows each hooked end of each cleat retainer to be pushed outwardly from the minor side of the pedal platform by elastically deforming the band. Thus, the two hooked ends which project above each surface of the pedal platform form a clamp. The clamp may be opened by pushing the ends of the cleat retainers away from the pedal platform. Once opened, however, the elastically deformed band applies pressure to each set screw which, in turn apply pressure to each cleat retainer, pushing the ends of the cleat retainer back towards the pedal body. The clamp may be used to grasp a specially adapted cleat, such as a Shimano SPD type cleat.
In one embodiment of the pedal, cooperation between pedal platform, cleat retainers, band and set screws allow each cleat retainer to pivot a certain amount about an axis defined by the set screws. The pivoting of the cleat retainers allows the hooked ends of each cleat retainer to move laterally with respect to the pedal platform. The lateral movement of the hooked ends allows a cleat that is inserted into the clamp to pivot, or float. In another embodiment of the pedal, an amount of float is provided by fixed cylindrical members interfacing with the cleat retainers.
In each embodiment, the peg-like structures (the screws of one embodiment and cylindrical members in the other) interfere with unconstrained movement of the cleat retainers thereby setting the amount of float provided. Naturally, the present invention may use any means which controls the location of cleat retainers relative to the pedal platform in a manner equivalent to the pegs.
An axle is included in the pedal assembly and is preferable formed from a lightweight alloy and treated to have a hard, wear resistant surface. The axle has a threaded inboard end and an outboard end adapted to include a circlip or other retaining means. The outboard end of the axle passes through a bore through the major sides of the band and pedal platform. The retaining means is then affixed to the outboard end, retaining the pedal platform and band on the axle. In a preferred embodiment, the plastic material of the band and pedal platform is impregnated with a lubricant allowing the axle to turn in the bore without the need for bearings. Alternatively, the bearings may be included in the bore in at least some embodiments.
Objects and advantages of the invention will be set forth, in part, in the description which follows and, in part, will be understood by those skilled in the art from the description or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.